Expandable laminates may be used in many areas, for example to replace corrugated board and paper board in various applications. Expandable laminates normally include an expandable material and a web or layer supporting the expandable material on one or both sides. Such expandable laminates, having a low density intermediate layer and supporting surface layers with high E-modulus, lead to materials which are flexurally rigid, and have low weight, which means that the laminates are not bulky during transport, but can be made flexurally rigid by expansion at the final destination. Examples of heat-expandable laminates are disclosed in DE20117662U1 and WO00/00408A1.
There is a need for thin and durable laminates. Specifically, it is desired to provide an improved expandable intermediate laminate, and to expand laminate structures including the intermediate laminate, and also to provide efficient processes for their production.